1. Field of the Invention
The invention relates to a battery charging device, more particularly to a battery charging device which is adapted to receive and charge battery packs of different sizes and specifications.
2. Description of the Related Art
Portable communications equipments, such as mobile telephones and the like, require a battery pack to operate the same. Since such communications equipments are available in different sizes and specifications, a corresponding type of battery pack is required. However, conventional battery pack charging devices, such as that shown in FIG. 1, are only capable of charging a maximum of two different types of battery packs. If the communications equipment is to be replaced by one which has a battery pack that does not fit the current battery pack charging device, a new battery pack charging device has to be purchased.
A battery pack charging device usually has a receiving space for receiving a battery pack therein, positive and negative electrical contacts for connecting electrically the battery pack to a charger circuit, and means for holding the battery pack in place inside the receiving space so as to achieve tight and proper electrical connection with the electrical contacts. The conventional battery charging device (A) shown in FIG. 1 is shown to have a first receiving space (a1) and a second receiving space (b1).
Referring to FIG. 2, the battery charging device (A) is shown to further have a pair of first positioning spring units (a2), a second positioning spring (a3) and a plurality of electrical contacts (a4) provided in the first receiving space (a1). The electrical contacts (a4) are disposed on a bottom end of the first receiving space (a1). When a battery pack (c1) is provided in the first receiving space (a1), the first positioning spring units (a2) tightly clamp the two sides of the battery pack (c1). The second positioning spring (a3) urges the battery pack (c1) so as to abut tightly against an opposite wall of the first receiving space (a1). The battery pack (c1) has contact terminals (not shown) which are provided on a bottom end of the same and which tightly contact the electrical contacts (a4) when the battery pack (c1) is received in the first receiving space (a1).
Referring to FIGS. 1 and 3, the battery charging device (A) further has a pair of first positioning spring units (b2), a second positioning spring (b4) and a plurality of electrical contacts (b3) provided in the second receiving space (b1). The electrical contacts (b4) are disposed on one side of the second receiving space (b1) opposite to the second positioning spring (b4). When a battery pack is provided in the second receiving space (b1), the first positioning spring units (b2) tightly clamp the two sides of the battery pack. The second positioning spring (b4) urges the battery pack so that the contact terminals (not shown) of the latter tightly contact the electrical contacts (b3).
Note that the springs (a2, b2) are deformed if a relatively large battery pack is forced into the receiving spaces (a1, b1). Positioning of a smaller battery pack in the receiving spaces (a1, b1) is difficult to achieve when the springs (a2, b2) are deformed, thereby preventing proper electrical connection between the battery pack and the charger circuit (not shown). Note also that the springs (a2, a3, b2, b4) are unable to position properly a relatively small battery pack in the receiving spaces (a1, b1). This can also prevent proper electrical connection between the battery pack and the charger circuit.